Intra-Panel Interface for Concurrent Display Driving and Touch Sensing in Touchscreen Displays

ABSTRACT

This application is directed to intra-panel communication in a touch display device in which a touch-integrated timing controller (TTCON) is coupled to touch-embedded source drivers (TSDs) via a plurality of forward links and a set of backward links. The forward links include a first subset of display forward links and a second subset of touch forward links. The TSDs are electrically coupled to a display panel including a plurality of display pixels and a plurality of touch sensors. The TTCON sends a display drive signal including display content data and display control data over the display forward links, and sends a touch control signal including an instruction to initiate an operation mode over the touch forward links. Upon receiving the touch control signal, the TSDs identify the instruction to initiate the operation mode, generate touch data accordingly, and return the touch data to the TTCON via the backward links.

TECHNICAL FIELD

This application relates to an intra-panel interface of a displaydevice, and in particular a bi-directional intra-panel interface forcommunicating data between a timing controller and one or more sourcedrivers in a display device having a touch-sensitive surface.

BACKGROUND

A typical pixel based display includes numerous source drivers (alsoreferred to as column drivers). Each of the source drivers drivesdisplay content data onto a specified column of a pixel array. A timingcontroller uses a timing controller-source driver interface to supplydisplay and control data to the source drivers. A conventional timingcontroller-source driver interface, however, is not optimized to captureand process data from widely adopted multi-function pixel displaypanels.

SUMMARY

This application is directed to a bi-directional and scalableintra-panel interface that is applied in a display device to couple atouch-integrated timing controller (TTCON) and one or moretouch-embedded source drivers (TSDs). The intra-panel interface includesat least a display forward link, a touch forward link, and a backwardlink. The display forward link and touch forward link are physicallyseparate from each other and are configured to transfer a display drivesignal and a touch control signal, respectively. In some embodiments,the display drive signal is scaled according to a resolution of displaypixels in the display panel, while the touch control signal is scaledbased on a size of a display panel of the display device independentlyof the display signal and without interfering with the display drivesignal.

In one aspect of this application, a method for intra-panelcommunication is implemented in an electronic device. A plurality offorward links and a set of backward links are established between aTTCON and one or more TSDs. The plurality of forward links including afirst subset of display forward links and a second subset of touchforward links. The one or more TSDs are electrically coupled to adisplay panel including a plurality of display pixels and a plurality oftouch sensors. The TTCON sends a display drive signal over the firstsubset of display forward links, and the display drive signal includesdisplay content data and display control data. The TTCON also sends atouch control signal over the second subset of touch forward links, andthe touch control signal includes an instruction to initiate anoperation mode on the one or more TSDs or the plurality of touchsensors. In response to receiving the touch control signal, the TSDsidentify the instruction to initiate the operation mode in the touchcontrol signal, generate touch data according to the operation mode, andreturn the touch data to the TTCON via the set of backward links.Particularly, in some embodiments, the first subset of display forwardlinks is physically separate from the second subset of touch forwardlinks. In another aspect, a non-transitory computer-readable medium hasone or more programs stored thereon. The one or more programs includeinstructions which when executed by one or more processors cause theprocessors of an electronic device to perform the above method.

In yet another aspect, an electronic device includes one or more TSDs, aTTCON and an intra-panel interface. The one or more TSDs are configuredto couple to a display panel that includes a plurality of display pixelsand a plurality of touch sensors. The TTCON is configured to provide adisplay drive signal and a touch control signal. The display drivesignal includes display content data and display control data, the touchcontrol signal including an instruction to initiate an operation mode onthe one or more TSDs or the plurality of touch sensors. The intra-panelinterface includes a plurality of forward links and a set of backwardlinks. The forward link includes a first subset of display forward linksand a second subset of touch forward links. The forward and backwardlinks are coupled between the TTCON and the one or more TSDs. The TTCONis configured to send the display drive signal to the one or more TSDsover the first subset of display forward links and send the touchcontrol signal to the one or more TSDs over the second subset of touchforward links. The one or more TSDs are configured to in response toreceiving the touch control signal, identify the instruction to initiatethe operation mode in the touch control signal, generate touch dataaccording to the operation mode, and return the touch data to the TTCONvia the set of backward links.

BRIEF DESCRIPTION OF DRAWINGS

The disclosed embodiments have other advantages and features, which willbe more readily apparent from the detailed description, the appendedclaims, and the accompanying figures (or drawings). A brief introductionof the figures is below.

FIG. 1 is a block diagram of an electronic system, in accordance withsome embodiments.

FIG. 2 is a block diagram illustrating a touch panel display subsystemhaving a scalable intra-panel interface (SIPI) between atouch-integrated timing controller (TTCON) and touch-embedded sourcedrivers (TSDs), in accordance with some embodiments.

FIG. 3 is a block diagram of a touch panel display subsystem having aTTCON and TSDs, in accordance with some embodiments.

FIG. 4 is a block diagram of a touch panel display subsystem in which aTTCON is coupled to a single TSD via an intra-panel interface, inaccordance with some embodiments.

FIG. 5A is a time diagram of a touch forward channel start signal 502, atouch link establishment signal, and a touch backward channel signalthat vary during a link establishment process, in accordance with someembodiments. FIGS. 5B and 5C illustrate data structures of a touchsensing configuration packet and a timing and power control packettransmitted over a touch forward link, in accordance with someembodiments.

FIG. 6A illustrates data structures of a touch forward channel signaland a touch backward channel signal during a link establishment process,in accordance with some embodiments. FIG. 6B illustrates data structuresof a touch forward channel signal and a touch backward channel signalincluding touch data returned to a TTCON, in accordance with someembodiments.

FIG. 7 illustrates a flowchart of a method for implementing intra-panelcommunication between a TTCON and one or more TSDs in a touch paneldisplay subsystem, in accordance with some embodiments.

DETAILED DESCRIPTION

The figures and the following description relate to embodiments by wayof illustration only. It should be noted that from the followingdiscussion, alternative embodiments of the structures and methodsdisclosed herein will be readily recognized as viable alternatives thatmay be employed without departing from the principles of what isclaimed.

Reference will now be made in detail to several embodiments, examples ofwhich are illustrated in the accompanying figures. It is noted thatwherever practicable similar or like reference numbers may be used inthe figures and may indicate similar or like functionality. The figuresdepict embodiments of the disclosed system (or method) for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles described herein.

FIG. 1 is a block diagram of an electronic system 100, in accordancewith some embodiments. In the electronic system 100, a processing device110 is electrically coupled to a display panel 125 including a displaypixel array. The display pixel array further includes a plurality ofdisplay pixels, a plurality of control lines, and a plurality of datalines. Each display pixel is powered between a display power supply anda ground supply. The processing device 110 operates in a display drivingmode in which a drive voltage is generated to drive a data line of eachdisplay pixel to enable display of a corresponding color on therespective display pixel with a respective luminance level. In someembodiments, the processing device 110 includes a processing core 112that provides display information (e.g., display content data of asequence of image frames) to a touch-integrated timing controller(TTCON) 104 and touch-embedded source drivers (TSDs) 106, such that theTSDs 106 can drive individual display pixels in the display panel 125 todisplay images or video clips based on the display information. In someembodiments, the processing core 112 includes some or all functions ofthe TTCON 104 and TSDs 106 (i.e., part or all of the TTCON 104 and TSDs106 is integrated in the processing core 112). Further, in the depictedembodiment, the display pixel array of the display panel 125 is coupledto the processing device 110 via a bus 124, and configured to receivedisplay driving signals (e.g., the drive voltages) from the processingdevice 110 via the bus 124. More specifically, the display drivingsignals are generated by the TSDs 106 of the processing device 110 andprovided to the display panel 125 via the bus 124.

In some embodiments, the display panel 125 further includes a touchsense array (e.g., a capacitive sense array), and the processing device110 can also operate in a touch sensing mode in addition to the displaydriving mode. Optionally, the touch sense array is formed on the samelayer of electrically conductive material that coats the bottom surfaceof the top encapsulation layer and provides electrodes for the displaypixel array. Optionally, the touch sense array is formed on analternative layer of conductive material that is distinct from the layerof electrically conductive material providing the common electrodes forthe display pixel array. The processing device 110 is configured tomeasure capacitance variations at the touch sense array and detect oneor more touches proximate to a surface of the display panel 125. In someembodiments, the processing device 110 alternates between the displaydriving mode and the touch sensing mode according to a predeterminedduty cycle (e.g., 80% in the display driving mode) for the displaydriving mode, and detects a contact with or a proximity to a touchsensing surface associated with the display pixel array withoutinterfering with display operations of the display pixel array.Conversely, in some embodiments, the processing device 110 operates inthe display driving mode and in the touch sensing mode independently ofeach other via the display pixel array and touch sense array,respectively.

In the touch sensing mode, capacitive touch sensors in the touch sensearray may be used to allow the TSDs 106 of the processing device 110 tomeasure self-capacitance, mutual capacitance, or any combinationthereof. In the depicted embodiment, the touch sense array is coupled tothe processing device 110 via a bus 122, and configured to provide touchsense signals to the TSDs 106 of the processing device 110 via the bus122. By these means, the processing device 110 detects the presence of atouch object 140, the presence of a stylus 130, or any combinationthereof on the touch sense array. In an example, the touch object is anactive stylus 130. The active stylus 130 operates as a timing master,and the processing device 110 adjusts the timing of the touch sensearray to match that of the active stylus 130.

In some embodiments, the processing device 110 includes analog and/ordigital general purpose input/output (“GPIO”) ports 107. The GPIO ports107 may be programmable. The GPIO ports 107 may be coupled to aProgrammable Interconnect and Logic (“PIL”), which acts as aninterconnect between the GPIO ports 107 and a digital block array of theprocessing device 110 (not shown). In some embodiments, the digitalblock array is configured to implement a variety of digital logiccircuits (e.g., DACs, digital filters, or digital control systems) usingconfigurable user modules (“UMs”). The digital block array may becoupled to a system bus. The processing device 110 may also includememory, such as random access memory (“RAM”) 105 and non-volatile memory(“NVM”) 114. The RAM 105 may be static RAM (“SRAM”). The non-volatilememory 114 may be flash memory, which may be used to store firmware(e.g., control algorithms executable by the processing core 112 toimplement operations described herein). The processing device 110 mayalso include a memory controller unit (“MCU”) 103 coupled to the memoryand to the processing core 112. The processing core 112 is a processingelement configured to execute instructions or perform operations. Theprocessing device 110 may include other processing elements as would beappreciated by one of ordinary skill in the art having the benefit ofthis disclosure. It should also be noted that the memory may be internalto the processing device 110 or external to it. In the case of thememory being internal, the memory may be coupled to a processingelement, such as the processing core 112. In the case of the memorybeing external to the processing device 110, the processing device 110is coupled to the other device in which the memory resides as would beappreciated by one of ordinary skill in the art having the benefit ofthis disclosure. Some or all of the operations of the processing core112 may be implemented in firmware, hardware, software, or somecombination thereof.

In some embodiments, the touch-integrated timing controller (TTCON) 104coupled to the processing core 112 is configured to generate a touchcontrol signal 120 and a display drive signal 121. The touch controlsignal 120 and display drive signal 121 are applied to the TSDs 106 todetect touch locations and drive individual display pixels,respectively. Specifically, the touch control signal 120 is used toenable the touch sensing mode in which self or mutual capacitance oftouch sensors of the touch sense array is optionally scanned by the TSDs106. Touch data 126 are returned from the TSDs 106 to the TTCON 104. Oneor more touch locations are thereby detected if one or more objectstouch a touch sensing surface of the electronic system 100.Alternatively, in some embodiments, the display drive signal 121includes display content data and display control data, and is used toenable the display driving mode. In such a display driving mode, theTSDs 106 provide a drive voltage to each display pixel of the displaypixel array based on the display content data. The display pixeldisplays an intended color with a certain luminance level upon receivingthe drive voltage.

Optionally, the touch control signal 120 and the display drive signal121 are time-multiplexed, and transmitted from the TTCON 104 to the TSDs106 via the same forward link. Optionally, the touch control signal 120and the display drive signal 121 are transmitted from the TTCON 104 tothe TSDs 106 via distinct and different forward links, and thereby,processed by the TSDs 106 independently of each other (e.g., during twoseparate durations of time, concurrently during the same duration oftime). As such, in some embodiments, an intra-panel communicationinterface between the TTCON 104 and TSDs 106 includes a set of displayforward links, a set of touch forward links, and a set of backwardlinks.

The processing device 110 may also include an analog block array (notshown) (e.g., a field-programmable analog array). The analog block arrayis also coupled to the system bus. An analog block array may beconfigured to implement a variety of analog circuits (e.g., ADCs oranalog filters) using, in some embodiments, configurable universalmachines. The analog block array may also be coupled to the GPIO 107.

The processing device 110 may include internal oscillator/clocks 116 anda communication block (“COM”) 118. In some embodiments, the processingdevice 110 includes a spread-spectrum clock (not shown). Theoscillator/clocks 116 provides clock signals to one or more of thecomponents of processing device 110. The communication block 118 may beused to communicate with an external component, such as an applicationprocessor 152, via an application interface (“I/F”) line 151. In someembodiments, the processing device 110 may also be coupled to anembedded controller 154 to communicate with the external components,such as a host 150. In some embodiments, the processing device 110 isconfigured to communicate with the embedded controller 154 or the host150 to send and/or receive data.

The processing device 110 may reside on a common carrier substrate suchas, for example, an integrated circuit (“IC”) die substrate, amulti-chip module substrate, or the like. In some embodiments, thecomponents of the processing device 110 may be one or more separateintegrated circuits and/or discrete components. In some embodiments, theprocessing device 110 may be one or more other processing devices knownby those of ordinary skill in the art, such as a microprocessor orcentral processing unit, a controller, a special-purpose processor, adigital signal processor (“DSP”), an application specific integratedcircuit (“ASIC”), a field programmable gate array (“FPGA”), or the like.

It is also noted that the embodiments described herein are not limitedto having a configuration of a processing device coupled to anapplication processor, but may include a system that measures thecapacitance on the touch sense array and sends the raw data to a hostcomputer 150 where it is analyzed by an application. In effect, theprocessing that is done by the processing device 110 may also be done inthe application processor. Specifically, in some embodiments, instead ofperforming the operations of the processing core 112 in the processingdevice 110, the processing device 110 may send the raw data orpartially-processed data to the host 150. The host 150, as illustratedin FIG. 1, may include decision logic 156 that performs some or all ofthe operations of the processing core 112. Operations of the decisionlogic 156 may be implemented in firmware, hardware, software, or acombination thereof. The host 150 may include a high-level ApplicationProgramming Interface (API) in applications 152 that perform routines onthe received data, such as compensating for sensitivity differences,other compensation algorithms, baseline update routines, start-up and/orinitialization routines, interpolation operations, or scalingoperations. The operations described with respect to the processing core112 may be implemented in the decision logic 156, the applications 152,or in other hardware, software, and/or firmware external to theprocessing device 110. In some other embodiments, the processing device110 is the host 150.

Each of the TTCON 104 and TSDs 106 may be integrated into the IC of theprocessing device 110, or in a separate IC that is optionally disposedin proximity to the display panel 125. In some embodiments, descriptionsof the TTCON 104 and TSDs 106 may be generated and compiled forincorporation into other integrated circuits. For example, behaviorallevel code describing the TTCON 104 or TSDs 106, or portions thereof,may be generated using a hardware descriptive language, such as VHDL orVerilog, and stored to a machine-accessible medium (e.g., CD-ROM, harddisk, floppy disk, or flash memory). Furthermore, the behavioral levelcode can be compiled into register transfer level (“RTL”) code, anetlist, or a circuit layout and stored to a machine-accessible medium.The behavioral level code, the RTL code, the netlist, and the circuitlayout may represent various levels of abstraction to describe the TTCON104 or TSDs 106.

It is noted that the components of the electronic system 100 may includeall of the components described above. In some embodiments, theelectronic system 100 includes fewer than all of the componentsdescribed above. In some embodiments, the electronic system 100 is usedin a tablet computer. In some embodiments, the electronic device is usedin other applications, such as a desktop computer, a notebook computer,a mobile handset, a personal data assistant (“PDA”), a keyboard, atelevision, a remote control, a monitor, a handheld multi-media device,a handheld media (audio and/or video) player, a handheld gaming device,a signature input device for point of sale transactions, an eBookreader, a global position system (“GPS”), or a control panel. Theembodiments described herein are not limited to touch screens ortouch-sensor pads for notebook embodiments.

FIG. 2 is a block diagram illustrating a touch panel display subsystem200 including a scalable intra-panel interface (SIPI) between atouch-integrated timing controller (TTCON) 104 and touch-embedded sourcedrivers (TSDs) 106, in accordance with some embodiments. The touch paneldisplay subsystem 200 includes one or more of: the TTCON 104, the one ormore TSDs 106, a plurality of forward links 216, a set of backward links218, an auxiliary status channel (ASC) 220, a power management bus (PD)222, a plurality of touch sensors 224, and a plurality of display pixels226. The TTCON 104 receives display content data and control data from asource device (e.g., a processing core 112 in FIG. 1), and generates adisplay drive signal and a touch control signal to provide the displaycontent data and control data to TSDs 106. The TTCON 104 includes adisplay interface 208 for receiving the display content data and controldata. The plurality of forward links 216 and the set of backward links218 form a bi-directional (SIPI) between the TTCON 104 and the TSDs 106of the touch panel display subsystem 200.

The display interface 208 receives the display content data from thesource device for display on the display panel 125. The display contentdata may include one or more combination of video, image data, and audiodata of various formats. The control data received via the displayinterface 208 includes address, timing, and other control informationused by the TTCON 104 to control the operation of the TSDs 106 or senddisplay status data 126 from one or more TSDs 106 to the TTCON 104. Inan example, a TSD 106 is embodied in an integrated circuit, die, orcomputing device included within a system that includes the touch paneldisplay subsystem 200. In another example, a TSD 106 is part of anexternal computing system, such as a set-top box, digital video diskplayer, or other external computing device that generates displaycontent data and control data suitable to be received by the TTCON 104over the display interface 208. In some embodiments, the displayinterface 208 is included in a graphics processing unit (GPU).

In some embodiments, the display interface 208 includes a main channel210 and a control channel 212. The main channel 210 carries the displaycontent data for display on the display panel. The control channel 212carries the control data that is associated with the display contentdata and transferred via bi-directional communication between each ofthe TSDs 106 and the TTCON 104. Example control data includes traininginformation, and test and debug information. The control channel 212also carries status information, including data error rate as measuredat one or a combination of the TSD 106 and the TTCON 104. In someembodiments, the control channel 212 carries the display control dataused by the display drive signal 121, and the display control dataincludes one or more of: vertical timing signals (e.g., vertical sync(VSYNC) or frame pulse (FP)), horizontal timing signals (e.g.,horizontal sync (HSYNC) or line pulse (LP)), and global timing signals(e.g., display refresh signals for refreshing a displayed image, clocksignals for operating gate drivers, and clock and latch enable foroperating TSDs 106).

The processor interface 214 of the TTCON 104 supports bi-directionalcommunication between an application processor 202 and the TTCON 104.The application processor 202 supports applications running in anoperating system environment. Example applications include applicationsdisplaying content on the display panel 125 for interaction with a user.For example, the application processor 202 interprets actions associatedwith interactions with content displayed in the display panel. Exampleactions may include navigation, content selection, or any other suitableaction interacting with the display content. In some embodiments, theapplication processor 202 is combined with the display interface 208.For example, the application processor 202 may be embedded in the GPUcore having a display interface 208. In some embodiments, the TTCON 104receives application data from the application processor 202 via theprocessor interface 214 and transmits touch sensor data received fromone or more TSDs 106 to the application processor 202 for furtherprocessing. In some embodiments, the TTCON 104 receives one or moretouch controller commands from an external processor via the processorinterface 214 to regulate the transmission of touch data 120 from theTSDs 106 to the TTCON 104, as further described in FIG. 4.

The ASC 220 of the TTCON 104 is a single line communication link thatenables the TSDs 106 to provide status information to the TTCON 104.Example status information includes link information such as symbol lockstatus or symbol error count. The ASC 220 is shared by multiple TSDs 106through a multi-drop configuration. In some embodiments, a single ASC220 connects all of the TSDs 106 in the touch panel display subsystem toa single TTCON 104. In another embodiment, multiple ASCs 220 may beused, with each ASC 220 connected to a subset of TSDs 106. In addition,multiple TTCONs 104 may be used to communicate with TSDs throughmultiple ASCs 220.

The PD 222 of the TTCON 104 enables the TTCON 104 to send power controlinformation to control the operation state of the TSDs 106.

The SIPI of the TTCON 104 includes a plurality of forward links 216 anda set of backward links 218. Each of the links 216 and 218 operates inaccordance with an SIPI standard. The plurality of forward links 216transmits display content data and control data from the TTCON 104 toeach TSD 106. The plurality of forward links 216 includes one or moredata channels, each data channel embodied as a differential pair ofconductors. In some embodiments, the one or more data channels areDC-coupled differential pairs with double termination. In someembodiments, the number of data channels included in the forward links216 is scalable. In an example, the plurality of forward links 216includes two data channels. The number of data channels may be greaterthan two to satisfy the maximum transmission throughput used for aspecific implementation of the touch panel display subsystem 200.

Further, the plurality of forward links 216 includes a first subset ofdisplay forward links 216A and a second subset of touch forward links216B for the purposes of transmitting display-related data and controlsignals separately from touch-related control signals. That said, thefirst subset of display forward links 216A is used to transmit a displaydrive signal 121 including display content data and display controldata, and the second subset of touch forward links 216B is used totransmit a touch control signal 120, independently of the displayforward links 216A. Each display forward link is coupled between theTTCON 104 and a respective TSD 106A to provide distinct display contentdata and control data to the respective TSD 106A. In contrast, in someembodiments, the set of touch forward links 216B is a multi-dropcommunication link coupled between the TTCON 104 and the TSDs 106 toprovide the TSDs 106 with the same touch control signal 120.

In some embodiments, each backward link 218 includes a singledifferential pair of signal conductors that transmit touch data fromeach TSD 106 to the TTCON 104. In some embodiments, the digital datatransmitted over each backward link 218 includes touch data 126 (e.g.,touch-related confirmation data, status data, touch sensor data)received from the touch sensors 224. In some embodiments, each backwardlink 218 has similar and identical electrical characteristics to each ofthe forward links 216.

Each TSD 106 receives multi-bit digital display content data and controldata from the TTCON 104 via the forward links 216, converts the displaycontent data to analog voltage levels, and provides the analog voltagelevels to pixels in the display panel 125. The transmission path formedby the output of each TSD 106 to the input of each pixel in a specificcolumn of pixels is referred to herein as an output channel or channel.A TSD 106 includes multiple output buffers, where each output bufferoperates to rapidly charge the column line capacitance of thecorresponding channel. The TSD 106 also receives touch sensor data fromone or more touch sensors 224 and sends the received touch sensor datato the TTCON 104 via the respective backward link 218 for furtherprocessing. In some embodiments, a group of TSDs 106 is coupled to asingle touch sensor 224.

Each touch sensor 224 measures physical interactions with a portion ofthe display panel and obtains information describing location, position,force, and interaction duration information of the physical interactionwith the display panel. For example, when an object (e.g., a finger)touches the display panel, the touch sensor 224 measures an analogsignal indicating the physical interaction, and the analog signal isconverted into digital data (i.e., touch data 126), in a correspondingTSD 106. The touch data 126 is then transmitted to the TTCON 104 over acorresponding backward link 218 for further processing. Touchinformation can be extracted in the TTCON 104 from the touch data 126.Example touch information includes position of a touch event relative toreference point on the display panel 125, force applied on the displaypanel 125, and touching duration indicating the duration of the touchevent. The touch sensor 224 may employ well-known methods, includingresistive and capacitive elements to detect a touch event. In someembodiments, the touch sensors 224 are integrated with a transparenttouch-sensitive material disposed on the display panel. Alternatively,the touch sensors 224 may be integrated into the display panel 125. Thenumber of touch sensors 224 varies based on the size of a display areaand a size of each touch sensor. Each touch sensor 224 is coupled to agroup of column drivers that are placed physically in proximity to thetouch sensor 224.

FIG. 3 is a block diagram of a touch panel display subsystem 300 havinga TTCON 104 and a plurality of TSDs 106, in accordance with someembodiments. The TTCON 104 and TSDs 106 are coupled to each other via anintra-panel interface including at least a set of display forward links216A, a set of touch forward links 216B, and a set of backward links218. Specifically, the TTCON 104 is coupled to each TSD 106 via adisplay forward link 216A, a touch forward link 216B, and a backwardlink 218. For each TSD 106, the display forward link 216A is configuredto transmit a display drive signal 121 including display content dataand display control data. For each TSD 106, the touch forward link 216Bis distinct from the display forward link 216A and configured totransmit a touch control signal 120 including an instruction to initiatean operation mode on the one or more TSDs or the plurality of touchsensors 224, and the backward link 218 is configured to return the touchdata 126 generated according to the operation mode to the TTCON 104. Thedisplay drive signal 121 transmitted via the display forward link 216Aand the touch data 126 returned via the backward link 218 are distinctfor each TSD 106, and therefore, each of the display forward link 216Aand backward link 218 is a point-to-point link. In some embodiments,each touch forward link 216B is a point-to-point link. Alternatively, insome embodiments, the touch control signal 120 is address aware and eachTSDs 106 has address assigned, and the touch forward link 216B is amulti-drop link connecting the TTCON 104 to all TSDs 106.

The touch forward link 216B is used to deliver touch configuration,touch timing control, and touch power control. For example, the touchcontrol signal 120 passed by the touch forward link 216B is used toenable functions including, but are not limited to, dividing a touchreceiver clock for a touch clock, dividing self synchronization by adedicated k-code, synchronizing operations of the touch sensors 224 andactive stylus 130, synchronizing a touch clock divider (e.g., a divider450A in FIG. 4), reading the touch data 126, configuring a touch analogfrontend (AFE) (e.g., a touch AFE 332 in FIG. 3), and providing a touchbackward channel clock source. In contrast, the touch data 126 collectedvia the backward link 218 includes, but is not limited to, touch sensordata, data concerning a touch forward link quality, a debug status, anda touch forward link lock/unlock indicator.

In some embodiments, commands, configurations and instructions/requestsare sent by the TTCON 104 through the forward links 216 only. From asystem control perspective, the TTCON 104 is a master, and the TSDs 106are slaves subject to the control of the TTCON 104.

The TTCON 104 includes a touch controller 302 and a display controller304 configured to control the TSDs 106 to measure touch sense data fromthe touch sensors 224 and drive the display pixels 226, respectively. Insome embodiments, display driving and touch sensing are synchronized,e.g., time-multiplexed with respective duty cycles. The displaycontroller 304 sends a touch slot signal 306 or a touch framesynchronization signal 308 to synchronize itself with the touchcontroller 302 based on a slot or an image frame, respectively.Optionally, each slot corresponds to a short duration of time separatingtwo rows of display content data, and touch sensing is implemented inthe short duration of time. A complete scan of the touch sensors 224 isconducted in a single slot or a plurality of slots separating multiplerows of display content data.

The touch controller 302 includes a CPU sub-system 310, a hardwareaccelerator 312, a timing control module 314, a touch forward channeltransmitter 316, a plurality of touch backward channel receivers 318,and a channel engine 320. The CPU subs-system 310, hardware accelerator312, and channel engines 320 are collectively called a touch sensingengine 460 in FIG. 4. A touch control signal 120 is generated by thetiming control module 314, and sends to the TSDs 106 via the touchforward channel transmitter 316. Touch data 126 returned by the TSDs 106are received by the touch backward channel receivers 318, and providedto channel engine 320 for further processing, e.g., identifying one ormore touch events on different areas of a touch sensing surface of thedisplay panel 125.

The touch forward channel transmitter 316 is coupled to a touch forwardchannel receiver 328 of each TSD 106, and configured to transmit thetouch control signal 120 to the touch forward channel receiver 328,e.g., in a serial data format. Each TSD 106 further includes adeserialization module 330, a touch AFE 332, a channel engine 334, and atouch backward channel transmitter 336. The deserialization module 330is configured to convert the touch control signal 120 to internal touchcontrol signals or recover a touch clock signal locally. The internaltouch control signals and the touch clock signal are used to control thetouch AFE 332 to measure touch sense data from the touch sensors 224 inthe display panel 125, e.g., scanning a subset or all touch sensors 224.The touch sense data is captured by the touch AFE 332 and pre-processedin the channel engine 334 before it is passed to the touch backwardchannel transmitter 336. The touch backward channel transmitter 336 iscoupled to a respective touch backward channel receiver 318 of the touchcontroller 302 via a respective backward link 218, thereby returning thetouch sense data to the touch controller 302 via the respective backwardlink 218.

In contrast, the display controller 304 of the TTCON 104 includes abuffer unit 322 (e.g., a frame buffer or a plurality of line buffers)and a plurality of display intra-panel transmitters 326. The buffer unit322 is configured to store display content data received from a displaysource 324 in frame or in line. The display intra-panel transmitters 326are configured to extract the display content data in the frame bufferor line buffers 322 and send the display content data to the displayforward links 216A coupled to the TSDs 106. On the TSD side, each TSD106 has a display intra-panel receiver 338 coupled to a respectivedisplay forward link 216A and configured to receive a subset of displaycontent data corresponding to the respective TSD 106. A display outputdriver 340 is configured to receive the subset of display content datafrom the display intra-panel receiver 338 and drive a subset of thedisplay pixels 226 using the subset of display content data, therebyallowing still images or video clips associated with the display contentdata to be displayed on the display panel 125.

FIG. 4 is a block diagram of a touch panel display subsystem 400 inwhich a TTCON 104 is coupled to a single TSD 106 via an intra-panelinterface, in accordance with some embodiments. Multiple TSDs 106 may becoupled to the TTCON 104. A single TSD 106 may be coupled to multipletouch sensors 224, and multiple TSDs 106 may be coupled to a touchsensor 224. For simplicity, in FIG. 4, one TTCON 104 and one TSD 106 areused to describe the forward link signal paths and backward link signalpaths. Similar signal paths may be employed to an implementationincluding multiple TSDs 106 and multiple touch sensors 205.

The TTCON 104 corresponds to a plurality of forward link paths and aplurality of backward link paths. The plurality of forward link pathsincludes a display forward link path and a touch forward link pathcoupled to each TSD 106. The touch forward link path includes a touchsensing engine 460, a scrambler 463, an encoder 465, a serializer 467, aflip flop 470, and a touch forward channel transmitter 316. The touchsensing engine 460 receives touch control data including one or moretouch controller commands from an external processor via the processorinterface 214 and generates a touch control signal 120 including thetouch controller commands. The touch controller commands indicate anoperation mode of the touch control signal 120. Examples of operationmodes include a link establishment mode, an active operation mode, anidle operation mode, and a sleep operation mode. The active operationmode indicates the touch sensor 224 is selected for detecting touchevents. The idle operation mode indicates no touch event is detectedwithin a threshold time value but the touch sensor 224 is still activefor detecting incoming touch events. The sleep operation mode indicatesthe touch sensor 224 is powered off or at a low power state and no touchevent is detected. In some embodiments, the touch controller command isused to determine that a transmission of touch sensor data 126 iscomplete in a backward link path. In some embodiments, the touch sensingengine 460 is external to the TTCON 104.

In some embodiments, the touch sensing engine 460 generates a receivercontrol signal directly based on the one or more touch controllercommands to enable or disable the touch backward channel receiver 318included in the backward link path of the TTCON 104. For example, thetouch sensing engine 460 generates a receiver control signal having afirst state to enable the touch backward channel receiver 318 to receiveinformation from the TSD 106 over the backward link when a touchcontroller command indicates the operation mode is an active operationmode. If the touch controller command indicates the operation mode is anidle or sleep operation mode, the touch sensing engine 460 generates areceiver control signal having a second state to maintain the touchbackward channel receiver 318 in a disabled state or cause the touchbackward channel receiver 318 to change state to a disable state. Thetouch sensing engine 460 may also generate a receiver control signalhaving a second state to disable the touch backward channel receiver 318when a determination is made by the touch sensing engine 460 thattransmission of the touch sensor data 126 from a TSD 106 over thebackward link 218 is complete, as further described below.

In some embodiments, a touch controller command is used to determine ifa transmission of the touch sensor data received from the touch sensor224 is complete. The touch controller command includes, among otherinformation, and indication of an expected amount of touch sensor datato be received from the touch panel. The TTCON 104 compares an amount ofthe touch data 126 returned by each TSD 106 or all TSDs 106 to acorresponding expected amount of touch sensor data. In accordance with adetermination that the amount of the touch data is equal to or greaterthan the expected amount of touch sensor data, the TTCON 104 disablesthe backward link 218, e.g., by disabling the touch forward channeltransmitter 316.

In some embodiments, the touch control signal 120 is generated based onthe touch controller commands, and includes a packet representing amulti-bit signal. The packet is separate from display data and thedisplay control signal 461 that are processed separately in the displayforward link path including the display forward link 216A. In someembodiments, the touch control signal 120 is transmitted over the touchforward link 216B to the TSD 106 during a vertical blanking period, orduring an intra-frame pause.

In some embodiments, the touch sensing engine 460 also generates touchcalibration data for calibrating the operation of the touch sensor 224.The touch calibration data is optionally embedded in the touch controlsignal 120. Alternatively, in some embodiments, the touch sensing engine460 sends the touch calibration data over the touch forward link 216B tothe TSD 106 via a different signal line. Likewise, display calibrationdata may be included in the display signal 121 that are sent to the TSD106 via the display forward link 216A or sent in a different signal lineother than the display forward link 216A.

In the TTCON 104, the scrambler 463 scrambles the touch control signal120 to generate scrambled touch control signal 120. The encoder 465encodes the scrambled composite data to generate encoded touch controlsignal 120. The encoder 465 may employ various encoding schemes,including 8b/10b. The serializer 467 converts the encoded touch controlsignal 120 into serial encoded touch control signal 120 and sends theserial encoded touch control signal 120 to the touch forward channeltransmitter 316 via the flip flop 470. The scrambler 463, the encoder465, the serializer 467, and the flip flop 470 receive a clock signalfrom the phase-locked loop (PLL) 455. In some embodiments, the clocksignal is embedded in the touch control signal 120. The touch forwardchannel transmitter 316 converts the serial encoded touch control signal120 into differential serial encoded touch control signal 120, andtransmits the differential serial encoded touch control signal 120 tothe touch forward channel receiver 336 included in TSD 106 over thetouch forward link 216B.

Referring to FIG. 4, the forward link components in the TSD 106 includea touch forward channel receiver 336, a clock data recovery circuit 483,a de-serializer 485, a decoder 487, a de-scrambler 490, and an outputdriver 340. The touch forward channel receiver 336 included in the TSD106 converts the differential serial encoded touch control signal 120received from the touch forward channel transmitter 316 via the touchforward link 216B into a serial bit stream encoded touch control signal120. The clock data recovery circuit 483 recovers a touch clock signalfrom the serial encoded touch control signal 120. The recovered touchclock signal generally has the same clock rate as the clock signalextracted from the touch control signal 120 transmitted from the TTCON104. For example, the recovered touch clock signal has the same clockrate as the clock signal output by the PLL 455 included in the TTCON104. The de-serializer 485 receives the serial encoded touch controlsignal 120 from the clock data recovery circuit 483 and converts theserial encoded touch control signal 120 into a multi-bit parallel touchcontrol signal 120. The decoder 487 receives the multi-bit paralleltouch control signal 120 that is encoded from the de-serializer 485 anddecodes the encoded touch control signal 120 to generate a decoded touchcontrol signal 120. The de-scrambler 490 de-scrambles the decoded touchcontrol signal 120 to generate descrambled touch control signal 120. Insome embodiments, the descrambled touch control signal 120 is the sameas the touch control signal 120 generated in the TTCON 104. Thedescrambled touch control signal 120 is used to control a touch sensinganalog frontend (AFE) 332 to measure touch sensor data 126 from thetouch sensor 224.

The backward link signal path in the TSD 106 includes the touch AFE 332,a scrambler 413, an encoder 415, a serializer 417, a flip flop 420, anda touch backward channel transmitter 336. The touch AFE 332 receives thetouch control signal 120 from the de-scrambler 490. In some embodiments,the touch AFE 332 compares the operation mode specified by the touchcontrol signal 120 with one or more settings data stored in the touchAFE 332 to determine whether to establish the backward link 218. Examplesettings may be a multi-bit value corresponding to an operation modesettings determined by the touch sensing engine 460. If the touch AFE332 determines that the received touch control signal 120 indicates theactive operation mode, the touch AFE 332 generates a transmitter controlsignal having a first state to enable the touch backward channeltransmitter 336 to establish the backward link 218. On the other hand,if the touch AFE 332 determines that the received touch control signal120 indicates an idle or sleep operation mode, the touch AFE 332generates the control signal having a second state to disable the touchbackward channel transmitter 336 to disestablish the backward link 218or maintain the backward link 218 in a disconnected state. Although notshown in FIG. 4, in some embodiments, the touch AFE 332 may also enableor disable other components included in the TSD 106 in a similar mannerwith respect to the touch backward channel transmitter 336.

In some embodiments, the touch AFE 332 also drives the touch sensor 224according to the touch control signal 120 received from the TTCON 104.For example, if the touch sensor 224 is a capacitive touch sensor,mutual capacitance is an amount of electrical charges between twoelectrodes. The touch AFE 332 charges the electrodes to generate anelectrical field defined according to the touch control signal 120between the two electrodes. When an object (e.g., a finger, or aninstrument) contacts the touch sensor 224 via the display panel, theobject acts as another charge conducting electrode to cause the mutualcapacitance between the two electrodes to decrease. The touch AFE 332receives the change of the mutual capacitance as a touch signal andconverts the touch signal into voltage signals for further processing,e.g., being sampled and digitalized to touch data 126.

The touch AFE 332 disables the touch backward channel transmitter 336 ifa transmission of the received touch sensor data is complete. In oneexample, the touch AFE 332 determines locally that the transmission ofthe received touch sensor data is complete using information receivedfrom the touch control signal 120 (e.g., a touch controller commandindicating an expected amount of touch sensor amount). In one example,the received information indicates the expected amount of the touchsensor data to be transmitted by the touch sensor 224. The touch AFE 332scans a corresponding portion of a touch panel to obtain touch sensordata 126. If the amount of the obtained touch sensor data matches theexpected amount of touch sensor data indicated in the touch controllercommand, the touch AFE 332 disables the touch backward channeltransmitter 336. In some embodiments, the touch AFE 332 also disablesother backward link components in the TSD 106 (e.g., the scrambler 413,the encoder 415 and the serializer 417) in accordance with adetermination that the transmission of received touch sensor data iscomplete.

In the TSD 106, each of the scrambler 413, encoder 415, serializer 417,flip flop 420, and touch backward channel transmitter 336 operates inmanner similar to the counterpart circuits included in the touch forwardpath of the TTCON 104. The scrambler 413 receives the converted touchsensor data 126 outputted by the touch AFE 332, and scrambles the touchsensor data and control signals from the touch AFE 332 to generatescrambled touch sensor data. The encoder 415 encodes the scrambled touchdata 126 to generate encoded touch sensor data. The serializer 417converts the encoded touch data 126 into serial encoded touch sensordata, and sends the serial encoded touch data 126 to the touch backwardchannel transmitter 336 via the flip flop 420. The flip flop 420receives the recovered touch clock signal from the clock data recoverycircuit 483 via the divider 450A and sends retimed touch sensor datasignal 126 to the touch backward channel transmitter 336. The divider450A performs a divide operation on the recovered touch clock togenerate a divided recovered clock with a reduced clock rate (alsoreferred to as a sub-rate) based on the divide ratio. The divide ratioof the divider 450A may be set to match the divide ratio of the divider450B included in the TTCON 104. In other embodiments, the recoveredclock is passed to the flip flop 420 without use of a divider 450A. Thetouch backward channel transmitter 336 converts the retimed serialencoded touch sensor data into differential serial encoded touch sensordata and transmits the differential serial encoded touch sensor dataover the backward link 218.

The backward link components in the TTCON 104 include a touch backwardchannel receiver 318, a clock data recovery circuit 433, a de-serializer435, a decoder 437, a de-scrambler 440, and a digital signal processor445. The touch backward channel receiver 318 included in the TTCON 104receives the differential serial encoded touch sensor data and generatesserial encoded touch sensor data. The touch sensing engine 460 generatesa receiver control signal having a second state to disable the touchbackward channel receiver 318 to disestablish the backward link 218. Insome embodiments (not shown in FIG. 4), the touch sensing engine 460 mayalso disable other components (e.g., the touch backward channel receiver318, the clock data recovery 233, the de-serializer 435, the decoder437, the de-scrambler 440, and the digital signal processor 445)included in the backward link of the TTCON 104 in a similar manner withrespect to the touch backward channel receiver 318.

The clock data recovery circuit 433 recovers the touch clock signalsfrom the serial encoded touch data 126 using the clock signal from thePLL 455 via the divider 450B. The touch sensor data output by the clockdata recovery circuit 433 is retimed at the same clock rate of the clockoutput by the PLL 455, which matches the clock rate of the touch sensordata 126 transmitted by the touch backward channel transmitter 336 overthe backward link 218. The de-serializer 435 converts the retimed serialencoded touch sensor data into multi-bit parallel encoded touch sensordata. The decoder 437 decodes the multi-bit parallel encoded touchsensor data to generate decoded touch data 126. The de-scrambler 440de-scrambles the decoded touch sensor data to generate descrambled touchsensor data. The digital signal processor 445 (also referred to as atouch signal processor) processes the touch sensor data for furtheranalysis. For example, the digital signal processor 445 analyzes thereceived touch sensor data to create a touch event by determiningtouching position, touching force applied on the display panel, angle ofthe touching force, magnitude of the touching force, touching duration,and other types of the touch events. Touch sensor data may also includeinformation indicating the type of instrument involved in the touchevent, such as finger, glove, pen or other instrument applied on thedisplay panel. In some embodiments, the digital signal processor 445performs initial process of the touch sensor data 126. The initialprocess of the touch sensor data 126 includes filtering out someunwanted components or features of the touch sensor data 126, enhancingsome components or features of the touch sensor data 126, compressing ordown-sampling the touch sensor data 126, or other suitable process usedfor digital signal processing. The digital signal processor 445transmits the processed touch sensor data 126 to the touch sensingengine 460 for creating the touch event. In some embodiments, thedigital signal processor 445 is embedded in the touch sensing engine460. After the touch sensor data 126 is processed, the touch sensingengine 460 transmits the processed touch sensor data 126 to theapplication processor 202 (not shown in FIG. 4).

FIG. 5A is a time diagram 500 of a touch forward channel start signal502, a touch link establishment signal 504, and a touch backward channelsignal 506 that vary during a link establishment process, in accordancewith some embodiments. Every time when a display panel 125 is powered onand before touch sensor data 126 can be measured and returned to theTTCON 104, the forward and backward links 216 and 218 are initialized,trained and established. That said, each TSD 106 also has three stagesincluding an initializing state, a link training state and a normaloperation state. In the initializing state, both the touch AFE 332 andPLL 455 are being prepared to reach a desired condition for measuringand transmitting touch sense data 126, while the touch backward channeltransmitter 336 outputs a default signal level (e.g., a low level “L”)in the touch forward channel start signal 502.

After an output of the PLL 455 is locked, the touch forward channeltransmitter 316 of the TTCON 104 changes to the link training state inwhich the touch forward channel transmitter 316 sends a low frequencyclock LTP0 (e.g., having 4-16 cycles at a frequency of 4 MHz) to resetthe touch forward channel receiver 328 in the TSDs 106, and sends atouch clock recovery signal LTP1 continuously to the touch forwardchannel receivers 328 until the receivers 328 are locked. In this linktraining stage, the touch forward channel receivers 328 start clockrecovery and phase alignment. The touch forward channel receivers 328 ofthe TSDs 106 are locked, indicating that clock recovery and phasealignment are completed. The touch forward channel transmitter 316 thensends a validity check signal LTP 2 to verify alignment. If there is noerror (invalid code or running disparity error) detected in response toLTP2, the TTCON 104 goes to a normal operation state and the forward andbackward links 216 and 218 are thereby established. As such, the touchlink establishment signal 504 includes LTP0, LTP1, LTP2, and a touchforward channel packet, and is sent from the TTCON 104 to the TSD 106 toestablish the touch forward link 216B.

The touch forward channel link establishment starts with link resetbased on LTP0 sent via the touch forward link 216B, then the link startsbit and symbol synchronization establishment. Link symbols transmittedby the touch forward channel transmitter 316 in this stage are arepetition of K28.7-(LTP1) and touch forward channel receivers 328should set lock signal high after it achieves both bit synchronizationand symbol lock. When detecting lock signals from touch forward channelreceivers in all TSDs 106, (e.g., TCHBKP and TCHBKN of the touchbackward channel signal 506 are low), the touch forward channeltransmitter 316 starts to send consecutive LTP2 to allow touch forwardchannel receiver to check a symbol boundary and determine if the touchforward link 216B is established correctly. In some embodiments, theminimum symbol number for LTP2 is 320.

FIGS. 5B and 5C are example data structures of a touch sensingconfiguration packet 520 and a timing and power control packet 540transmitted over a touch forward link 216B, in accordance with someembodiments. During the normal operation state, the touch forwardchannel transmitter 316 starts to send the touch control signal 120including encoded touch forward channel packets to the touch forwardchannel receivers 328 in accordance with a determination that thereceivers 328 are locked. The touch forward channel packets areconsistent with the touch controller commands received by the touchsensing engine 460 and used to generate the touch control signal 120.The touch forward channel packet 520 corresponds to an instruction toinitiate an active operation mode on a respective TSD 106 and touchsensors 224. In response to receiving the touch control signal 120including the touch forward channel packet 520, the instruction toinitiate the active mode is identified, and touch data 216 is generatedand returned to the TTCON 204.

The touch forward channel receivers 328 decode and restore the touchforward channel packets 520 in the touch control signal 120 transmittedover the touch forward channels 216B, thereby controlling the touch AFE332 to measure touch sensor data 126 from the touch sensors 224. Thetouch configuration packet 520 can either be frame based or slot basedconfiguration registers, and both have the same structure. The touchconfiguration packet 520 has a start field 522, a header field 524 and adata field 526 including touch configuration data used to control thetouch AFE 332 to measure touch sensor data from the touch sensors 224.The start field 522 includes data scrambling configuration, which isoptionally selected between data scrambling enabled and data scramblingenabled with seed reset. In an example, the header field 524 has 5 bytes(Bytes 0, 1, 2, 3 and 4). Byte 0 selects one of the TSDs 106 and defineswhether an operation is implemented to write data to, read data from, orburst read from the selected TSD 106. Bytes 1 and 2 are used to define astart page number and a start address. Bytes 3 and 4 are used to definea length of the relevant data (e.g., the touch sensor data measured fromthe touch sensors 224).

The touch configuration packet 520 can be used to read back the TSD'sstatus, such as link error for quality monitoring, debug status. In someembodiments, when it is set to a read back mode, the touch configurationpacket 520 only consists of 4 bytes Start and 5 bytes header. The readand burst read command are for status register readback. The onlydifference is that the status register is sent back after the touch data126 if a read command is received, and the status register is sent backimmediately for Burst Read command. Before a touch slot is configured,burst read is used to avoid waiting for the touch data 126 and causing adead lock. It is optionally used during a touch timing debug stage.

Referring to FIG. 5C, the timing and power control packet 540 has apriority over the touch configuration packet 520, and is optionallyinserted anywhere in the touch forward channel packet of the touch sensesignal. In some embodiments, the TTCON 104 is configured to avoid aconflict between the time configuration packet 520 and the timing andpower control packet 540 in the touch control signal 120 sent to theTSDs 106. In some embodiments, the timing and power control packet 540includes a backward channel control data (e.g., “backward channel start”and “backward channel end”) controlling a start and an end of thecorresponding backward channel 218. In accordance with a determinationthat the backward channel control data of the timing and power controlpacket 540 indicates a request for starting/ending the correspondingbackward channel 218, the corresponding backward channel 218 isstarted/terminated. In some embodiments, the timing and power controlpacket 540 includes a forward channel control data controlling an end ofthe corresponding touch forward channel 216B. In these embodiments, thetiming and power control packet 540 optionally corresponds to aninstruction to initiate an idle or sleep mode in which the touch forwardchannel 216B and/or the backward channel 218 of each TSD 106 isdisabled.

FIG. 6A illustrates data structures 600 of a touch forward channelsignal 602 and a touch backward channel signal 604 during a linkestablishment process, in accordance with some embodiments. The TSDs 106have a standby state, link training pattern transmission state and touchdata/debug data transmission state. When power is on, the touch backwardchannel transmitter 336 must be in the Standby State and wait for“backward channel start” command 606 from the touch forward channelpacket 520 of the touch control signal 120, e.g., the touch forwardchannel signal 602. During this state, an output of the touch backwardchannel transmitter 336 remains its default low (‘L’) 608. After the“backward channel start” command 606 is received, the touch backwardchannel transmitter 336 changes its state into the link training patterntransmission state. In the link training pattern transmission state, thetouch backward channel transmitter 328 will send LTP1 (optional) andLTP2 pattern sequentially to train the touch backward channel receivers318 for a period of time. After that, it keeps sending LTP2 patternuntil touch data 126 is ready for transmission. When the touchdate/status data 126 is ready for transmission, the touch backwardchannel transmitter 336 starts to send encoded touch packets to thetouch backward channel receiver 318 until the data transmission iscompleted. The touch backward channel receiver 318 returns to initialstate if it receives “backward channel end” command (e.g., BackCh End626 in FIG. 6B) from the touch forward channel packet 520.

The touch backward channel is started by the TTCON 104 through command“backward channel start” 606 transmitted in the touch control signal120. In some embodiments, the touch backward channel only can be startedwhen both TCHBKP and TCHBKN are low, which indicates that the touchforward channel receivers 328 are in lock states (the touch backwardchannel transmitters 336 are also ready to start). In some embodiments,a duration between times T0 and T1 corresponds to a clock recoverystage. The signal LTP1 is programmable with 0-4096 symbols for thereceivers 318 to achieve a bit and symbol lock state. A duration betweentimes T1 and T2 corresponds to a symbol synchronization checking stagein which the signal LTP2 is repeated.

FIG. 6B illustrates data structures 620 of a touch forward channelsignal 622 and a touch backward channel signal 624 including touch data126, in accordance with some embodiments. The touch data packetcorresponding to the touch sense data 126 measured from touch sensors224 starts with SOD, is followed by touch scan data and BS, and endswith stuffing data. An idle pattern can be inserted into the touch data126 when it is needed. The SOD optionally selects one of four scramblingoptions: touch data scrambling disabled, touch data scrambling enabled,touch data scrambling enabled with seed reset, and burst read datascrambling enabled with seed reset. In some embodiments, to make touchdata transfer design more flexible, or when touch data transfer is atin-continue mode, an idle pattern is inserted if data is empty.

Referring to 5A-5C and 6A-6B, after the touch forward link 216B isestablished, the touch forward channel transmitter 316 sends a touchcontrol signal 120 from the TTCON 104 to the touch forward channelreceiver 328 included in each TSD 106 over one or more forward links216B. The touch control signal 120 specifies an operation mode andincludes a touch forward channel packet 520 in an active operation mode.In the active operation mode, the disclosed bi-directional scalableintra-panel interface allows transmission of digital touch sense data126 between a TTCON 104 and one or more TSD 106. In some embodiments, atouch receiver 318 is included in the one or more TSDs 106, and adigital signal processor is included in the TTCON 104. In such aconfiguration, a touch sensing engine 460 can be embedded in the TTCON104 to simplify system design and to save cost. The touch control signal120 may be separated from a display signal 122 and transferred from theTTCON 104 to the one or more TSDs 106 via a separate forward link 216B.Thus, no separate backward link control channel is needed. Moreover, foreach TSD 106, both touch forward link 216B and backward link 218 includescramblers and encoders to reduce disturbances that affect the forwardlink 216B and the backward link 218. The touch sensor data 126 istransmitted to the TTCON 104 over the backward link 218 at a clock ratederived from the touch clock signal extracted from the touch controlsignal 120, therefore, no extra PLL is needed in the backward link path.

FIG. 7 provides a flowchart of a method 700 for implementing intra-panelcommunication between a TTCON 104 and one or more TSD 106 in a touchpanel display subsystem, in accordance with some embodiments. The method700 includes establishing (702) a plurality of forward links 216 and aset of backward links 218 between a touch-integrated timing controller(TTCON) 104 and one or more touch-embedded source drivers (TSDs) 106.The plurality of forward links 216 includes (702) a first subset ofdisplay forward links 216A and a second subset of touch forward links216B. The one or more TSDs 106 are (702) electrically coupled to adisplay panel 125 including a plurality of display pixels 226 and aplurality of touch sensors 224. In some embodiments, during the courseof establishing the forward and backward links, the TTCON 204 sends alow frequency reset signal (e.g., LTP0 in FIG. 5A) to the one or moreTSDs 206 over the second subset of touch forward links 216B. In responseto receiving the low frequency reset signal, touch control logic in theone or more TSDs 206B are reset and synchronized, thereby allowing theTSDs 206 to recover from an abnormal state. After the forward andbackward links 216 and 218 are established, the TTCON 104 sends (704) adisplay drive signal over the first subset of display forward links216A, and the display drive signal includes display content data anddisplay control data. The TTCON 104 sends (706) a touch control signal120 over the second subset of touch forward links 216B. The touchcontrol signal 120 includes (706) an instruction to initiate anoperation mode on the one or more TSDs 106 or the plurality of touchsensors 224. In response to receiving the touch control signal 120, theTSDs 106 identify (708) the instruction to initiate the operation modein the touch control signal 120, generate touch data according to theoperation mode, and return the touch data to the TTCON via the set ofbackward links 218.

In some embodiments, the first subset of display forward links 216A isphysically separate from the second subset of touch forward links 216B.In some embodiments, the one or more TSDs 106 recover a touch clocksignal from the touch control signal 120 provided by the second subsetof touch forward links 216B. The touch clock signal has a touch clockfrequency, and touch sensor data is sensed from the plurality of touchsensors 224 based on the touch clock signal. Further, in someembodiments, the one or more TSDs 106 recover a display clock signalfrom the display drive signal provided by the first subset of displayforward links 216A. The display clock signal has a display clockfrequency that is distinct from the touch clock frequency. The displaypanel is driven using the display content data based on the displayclock signal. Additionally, in some embodiments, the touch data returnedover the set of backward links 218 has a data rate that is equal to ordivided from the touch clock frequency based on a panel size of thedisplay panel.

In some embodiments, the operation mode is an active operation mode. Togenerate the touch data 126, the one or more TSDs 106 scan a subset ofthe plurality of touch sensors to obtain a plurality of touch sensesignals, generate touch sensor data based on the plurality of touchsense signals, and serialize the touch sensor data to be returned to theTTCON via the set of backward links. Further, in some embodiments, thetouch control signal 120 includes a set of multibit control data packetsconfigured to define the instruction to initiate the active operationmode, and the set of multibit control data packets includes one or moreof: a configuration data packet, a timing control packet, and a powercontrol packet. More details on the multibit control data packets arediscussed above with reference to FIGS. 5A-5C.

In some embodiments, during the course of establishing the forward andbackward links, the one or more TSDs 106 receive a reset clock signalfor resetting the second subset of touch forward links; receive apredefined train of link symbols (e.g., LTP1) via the second subset oftouch forward links; in accordance with an identification of thepredefined train of link symbols, setting a lock signal; receive avalidity check signal (e.g., LTP2); and in response to receiving thevalidity check signal, determine a symbol boundary and whether thesecond subset of touch forward links 216 is established properly.

In some embodiments, the touch control signal 120 is sent over thesecond subset of touch forward links 216B to the one or more TSDs 106during a vertical blanking period. In some embodiments, the touchcontrol signal 120 is sent over the second subset of touch forward linksto the one or more TSDs during an intra-frame pause.

In some embodiments, the operation mode is an idle operation mode. Inresponse to receiving the touch control signal 120, the TTCON 104 andTSDs 106 maintain the set of backward links 218 in a disconnected state.

In some embodiments, a touch clock signal is extracted from the touchcontrol signal 120. The touch data 126 is returned to the TTCON 104 overthe set of backward links 218 at a data clock rate derived from thetouch clock signal. Further, in some embodiments, the data clock rate isthe same rate or sub-rate of the touch clock signal extracted from thetouch control signal 120. Additionally, the one or more TSDs 106 includea scrambler (e.g., scrambler 413 in FIG. 4) coupled to the set ofbackward links, and the touch data 126 is scrambled using the scramblerof the one or more TSDs prior to being returned via the set of backwardlinks 218.

In some embodiments, in accordance with a determination that returningthe touch data 126 is completed, the set of backward links 218 isdisabled, e.g., by disabling a touch backward channel transmitter 336 inthe one or more TSDs 106 or a touch backward channel receiver 318 of theTTCON 104. The touch control signal 120 is updated to include aninstruction to initiate an idle operation mode. The second subset oftouch forward links 216B is disabled in accordance with the touchcontrol signal 120, e.g., by disabling a touch forward channel receiver328 in the one or more TSDs 106 or a touch forward channel transmitter316 in the TTCON 104.

In some embodiments, the TTCON 104 receives a touch controller commandindicating an expected amount of touch sensor data to be returned by theone or more TSDs, receives the touch data 126 from the one or more TSDs106, compares an amount of the touch data 126 to the expected amount oftouch sensor data, and disables the set of backward links 218 when theamount of the touch data 126 is equal to or greater than the expectedamount of touch sensor data. Alternatively, in some embodiments, theinformation of the expected amount of touch sensor data is provided tothe TSDs 106, and the TSDs 106 compare an amount of the touch data 126with the expected amount of touch sensor data, and disable the set ofbackward links 218 (e.g., by disabling a touch backward channeltransmitter 336 in the one or more TSDs 106).

In some embodiments, each touch forward link 216B is coupled to a touchforward channel transmitter 316 of the TTCON 104 and a respective touchforward channel receiver 328 of the one or more TSDs 106. Each backwardlink 218 is coupled to a respective touch backward channel transmitter336 of the one or more TSDs 106 and a respective touch backward channelreceiver 318 of the TTCON 104.

In some embodiments, each forward link 216 operates in accordance with ascalable intra-panel interface format.

In some embodiments, the TTCON 104 receives one or more touch controllercommands from an external processor, and generates the touch controlsignal 120 based on the one or more touch controller commands.

In some embodiments, a touch sensing engine 460 is coupled to the TTCON104, and configured to enable the second subset of touch forward links216B and the set of backward links 218 when the one or more touchcontroller commands indicate the operation mode specified by the touchcontrol signal 120 is a link establishment mode or an active operationmode. Alternatively, in some embodiments, a touch sensing engine iscoupled to the TTCON, and configured to disable the second subset oftouch forward links 216B and the set of backward links 218 when the oneor more touch controller commands indicates the operation mode specifiedby the touch control signal 120 is an idle operation mode.

In some embodiments, the one or more TSDs 106 include a first TSD (e.g.,106-1 in FIG. 3) and a second TSD (e.g., 106-n in FIG. 3). A first setof display content data is sent to the first TSD via a first displayforward link. A second set of display content data is sent to the secondTSD via a second display forward link. The same touch control signal 120is sent to the first TSD and the second TSD via a same touch forwardlink. That said, a 1 to N multi-drop link between the TTCON 104 and TSDs106 is formed.

In one aspect, this application is directed to an electronic deviceincluding one or more TSDs 106, a TTCON 104, a plurality of forwardlinks 216, and a set of backward links 218. The electronic device isconfigured to implement the method 700 as described with reference toFIG. 7. In another aspect, this application is directed to anon-transitory computer-readable medium, having instructions storedthereon, which when executed by one or more processors cause theprocessors to perform the method 700.

Throughout this specification, plural instances may implementcomponents, operations, or structures described as a single instance.Although individual operations of one or more methods are illustratedand described as separate operations, one or more of the individualoperations may be performed concurrently, and nothing requires that theoperations be performed in the order illustrated. Structures andfunctionality presented as separate components in example configurationsmay be implemented as a combined structure or component. Similarly,structures and functionality presented as a single component may beimplemented as separate components. These and other variations,modifications, additions, and improvements fall within the scope of thesubject matter herein.

Certain embodiments are described herein as including logic or a numberof components, modules, or mechanisms. A hardware module is tangibleunit capable of performing certain operations and may be configured orarranged in a certain manner. In example embodiments, one or morecomputer systems (e.g., a standalone, client or server computer system)or one or more hardware modules of a computer system (e.g., a processoror a group of processors) may be configured by software (e.g., anapplication or application portion embodied as executable instructionsor code) as a hardware module that operates to perform certainoperations as described herein.

In various embodiments, a hardware module may be implementedmechanically or electronically. For example, a hardware module maycomprise dedicated circuitry or logic that is permanently configured(e.g., as a special-purpose processor, such as a field programmable gatearray (FPGA) or an application-specific integrated circuit (ASIC)) toperform certain operations. A hardware module may also compriseprogrammable logic or circuitry (e.g., within a general-purposeprocessor or other programmable processor) that is temporarilyconfigured by software to perform certain operations. It will beappreciated that the decision to implement a hardware modulemechanically, in dedicated and permanently configured circuitry, or intemporarily configured circuitry (e.g., configured by software) may bedriven by cost and time considerations.

The various operations of example methods described herein may beperformed, at least partially, by one or more processors that aretemporarily configured (e.g., by software) or permanently configured toperform the relevant operations. Whether temporarily or permanentlyconfigured, such processors may constitute processor-implemented modulesthat operate to perform one or more operations or functions. The modulesreferred to herein may, in some example embodiments, compriseprocessor-implemented modules.

Some portions of this specification are presented in terms of algorithmsor symbolic representations of operations on data stored as bits orbinary digital signals within a machine memory (e.g., a computermemory). These algorithms or symbolic representations are examples oftechniques used by those of ordinary skill in the data processing artsto convey the substance of their work to others skilled in the art. Asused herein, an “algorithm” is a self-consistent sequence of operationsor similar processing leading to a desired result. In this context,algorithms and operations involve physical manipulation of physicalquantities. Typically, but not necessarily, such quantities may take theform of electrical, magnetic, or optical signals capable of beingstored, accessed, transferred, combined, compared, or otherwisemanipulated by a machine. It is convenient at times, principally forreasons of common usage, to refer to such signals using words such as“data,” “content,” “bits,” “values,” “elements,” “symbols,”“characters,” “terms,” “numbers,” “numerals,” or the like. These words,however, are merely convenient labels and are to be associated withappropriate physical quantities.

Unless specifically stated otherwise, discussions herein using wordssuch as “processing,” “computing,” “calculating,” “determining,”“presenting,” “displaying,” or the like may refer to actions orprocesses of a machine (e.g., a computer) that manipulates or transformsdata represented as physical (e.g., electronic, magnetic, or optical)quantities within one or more memories (e.g., volatile memory,non-volatile memory, or a combination thereof), registers, or othermachine components that receive, store, transmit, or displayinformation.

As used herein any reference to “some embodiments” or “an embodiment”means that a particular element, feature, structure, or characteristicdescribed in connection with the embodiment is included in at least someembodiments. The phrase “in some embodiments” in various places in thespecification is not necessarily all referring to the same embodiment.

Some embodiments may be described using the expression “coupled” and“connected” along with their derivatives. For example, some embodimentsmay be described using the term “coupled” to indicate that two or moreelements are in direct physical or electrical contact. The term“coupled,” however, may also mean that two or more elements are not indirect contact with each other, but yet still co-operate or interactwith each other. The embodiments are not limited in this context.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

In addition, use of the “a” or “an” are employed to describe elementsand components of the embodiments herein. This is done merely forconvenience and to give a general sense of the invention. Thisdescription should be read to include one or at least one and thesingular also includes the plural unless it is obvious that it is meantotherwise.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative structural and functional designs for abi-directional scalable intra-panel interface disclosed herein. Thus,while particular embodiments and applications have been illustrated anddescribed, it is to be understood that the disclosed embodiments are notlimited to the precise construction and components disclosed herein.Various modifications, changes and variations, which will be apparent tothose skilled in the art, may be made in the arrangement, operation anddetails of the method and apparatus disclosed herein without departingfrom the spirit and scope described.

What is claimed is:
 1. A method for intra-panel communication, themethod comprising: establishing a plurality of forward links and a setof backward links between a touch-integrated timing controller (TTCON)and one or more touch-embedded source drivers (TSDs), the plurality offorward links including a first subset of display forward links and asecond subset of touch forward links, wherein the one or more TSDs areelectrically coupled to a display panel including a plurality of displaypixels and a plurality of touch sensors; sending, by the TTCON, adisplay drive signal over the first subset of display forward links, thedisplay drive signal including display content data and display controldata; sending, by the TTCON, a touch control signal over the secondsubset of touch forward links, the touch control signal including aninstruction to initiate an operation mode on the one or more TSDs or theplurality of touch sensors; and in response to receiving the touchcontrol signal, identifying the instruction to initiate the operationmode in the touch control signal, generating touch data according to theoperation mode, and returning the touch data to the TTCON via the set ofbackward links.
 2. The method of claim 1, wherein the first subset ofdisplay forward links is physically separate from the second subset oftouch forward links.
 3. The method of claim 1, further comprising, inthe one or more TSDs: recovering a touch clock signal from the touchcontrol signal provided by the second subset of touch forward links, thetouch clock signal having a touch clock frequency; and sensing touchsensor data from the plurality of touch sensors based on the touch clocksignal.
 4. The method of claim 3, further comprising, in the one or moreTSDs: recovering a display clock signal from the display drive signalprovided by the first subset of display forward links, the display clocksignal having a display clock frequency that is distinct from the touchclock frequency; driving the display panel using the display contentdata based on the display clock signal.
 5. The method of claim 3,wherein the touch data returned over the set of backward links has adata rate that is equal to or divided from the touch clock frequencybased on a panel size of the display panel.
 6. The method of claim 1,wherein the operation mode is an active operation mode, and generatingthe touch data according to the operation mode further comprises, at theone or more TSDs: scanning a subset of the plurality of touch sensors toobtain a plurality of touch sense signals; generating touch sensor databased on the plurality of touch sense signals; and serializing the touchsensor data to be returned to the TTCON via the set of backward links.7. The method of claim 6, wherein the touch control signal includes aset of multibit control data packets configured to define theinstruction to initiate the active operation mode, and the set ofmultibit control data packets includes one or more of: a configurationdata packet, a timing control packet, and a power control packet.
 8. Themethod of claim 1, wherein establishing the plurality of forward linksand the set of backward links further comprises, at the one or moreTSDs: receiving a reset clock signal for resetting the second subset oftouch forward links; receiving a predefined train of link symbols viathe second subset of touch forward links; in accordance with anidentification of the predefined train of link symbols, setting a locksignal; receiving a validity check signal; and in response to receivingthe validity check signal, determining a symbol boundary and whether thesecond subset of touch forward links is established properly.
 9. Themethod of claim 1, wherein the touch control signal is sent over thesecond subset of touch forward links to the one or more TSDs during oneof a vertical blanking period and an intra-frame pause.
 10. The methodof claim 1, wherein the operation mode is an idle operation mode,further comprising: in response to receiving the touch control signal,maintaining the set of backward links in a disconnected state.
 11. Anelectronic device, comprising: one or more TSDs configured to couple toa display panel including a plurality of display pixels and a pluralityof touch sensors; a TTCON configured to provide a display drive signaland a touch control signal, the display drive signal including displaycontent data and display control data, the touch control signalincluding an instruction to initiate an operation mode on the one ormore TSDs or the plurality of touch sensors; a plurality of forwardlinks and a set of backward links, the forward link including a firstsubset of display forward links and a second subset of touch forwardlinks, wherein the forward and backward links are coupled between theTTCON and the one or more TSDs; wherein the TTCON is configured to sendthe display drive signal to the one or more TSDs over the first subsetof display forward links and send the touch control signal to the one ormore TSDs over the second subset of touch forward links; and wherein theone or more TSDs are configured to in response to receiving the touchcontrol signal, identify the instruction to initiate the operation modein the touch control signal, generate touch data according to theoperation mode, and return the touch data to the TTCON via the set ofbackward links.
 12. The electronic device of claim 11, wherein the oneor more TSDs are further configured to extract a touch clock signal fromthe touch control signal, wherein the touch data is returned to theTTCON over the set of backward links at a data clock rate derived fromthe touch clock signal.
 13. The electronic device of claim 12, whereinthe data clock rate is the same rate or sub-rate of the touch clocksignal extracted from the touch control signal.
 14. The electronicdevice of claim 11, wherein a touch sensing engine is coupled to theTTCON, and configured to enable the second subset of touch forward linksand the set of backward links when the one or more touch controllercommands indicates the operation mode specified by the touch controlsignal is a link establishment mode or an active operation mode.
 15. Theelectronic device of claim 11, wherein a touch sensing engine is coupledto the TTCON, and configured to disable the second subset of touchforward links and the set of backward links when the one or more touchcontroller commands indicates the operation mode specified by the touchcontrol signal is an idle operation mode.
 16. A non-transitorycomputer-readable medium, having one or more programs stored thereon,the one or more programs including instructions which when executed byone or more processors cause the processors of an electronic device toperform: establishing a plurality of forward links and a set of backwardlinks between a touch-integrated timing controller (TTCON) and one ormore touch-embedded source drivers (TSDs), the plurality of forwardlinks including a first subset of display forward links and a secondsubset of touch forward links, wherein the one or more TSDs areelectrically coupled to a display panel including a plurality of displaypixels and a plurality of touch sensors; sending, by the TTCON, adisplay drive signal over the first subset of display forward links, thedisplay drive signal including display content data and display contentdata; sending, by the TTCON, a touch control signal over the secondsubset of touch forward links, the touch control signal including aninstruction to initiate an operation mode on the one or more TSDs or theplurality of touch sensors; and in response to receiving the touchcontrol signal, identifying the instruction to initiate the operationmode in the touch control signal, generating touch data according to theoperation mode, and returning the touch data to the TTCON via the set ofbackward links.
 17. The non-transitory computer-readable medium of claim16, the one or more programs further comprising instructions for:disabling the set of backward links; updating the touch control signalto include an instruction to initiate an idle operation mode; anddisabling the second subset of touch forward links in accordance withthe touch control signal.
 18. The non-transitory computer-readablemedium of claim 16, the one or more programs further comprisinginstructions for: receiving information of an expected amount of touchsensor data to be returned by the one or more TSDs; receiving the touchdata from the one or more TSDs; comparing an amount of the touch data tothe expected amount of touch sensor data; and disabling communicationvia the set of backward links when the amount of the touch data is equalto or greater than the expected amount of touch sensor data.
 19. Thenon-transitory computer-readable medium of claim 16, wherein the one ormore TSDs include a first TSD and a second TSD, and the one or moreprograms further comprise instructions for: sending a first set ofdisplay content data to the first TSD via a first display forward link;sending a second set of display content data to the second TSD via asecond display forward link; and sending the touch control signal to thefirst TSD and the second TSD via a same touch forward link.
 20. Thenon-transitory computer-readable medium of claim 16, whereinestablishing the plurality of forward links and the set of backwardlinks between the TTCON and the TSDs further comprises: sending a lowfrequency reset signal from the TTCON to the one or more TSDs over thesecond subset of touch forward links; and in response to receiving thelow frequency reset signal, resetting and synchronizing the one or moreTSDs.